Hydraulic properties of soil cores from untrafficked and trafficked areas

The hydraulic conductivity is an important soil parameter that is both difficult and time consuming to measure directly. Several methods have been proposed to estimate soil hydraulic conductivity indirectly. This paper focuses on one method of predi.:ting hydraulic conductivity from knowledge of the soil water retention curve. Water retention curves were measured for 15 undisturbed soil cores. Unsaturated hydraulic conductivity of the same 15 soil cores also was determined directly by using unit gradient measurements. An equation was fitted to each of the retention curves, and a procedure using the fitting parameters was implemented to predict hydraulic conductivity of each core. Predicted and observed hydraulic conductivities are compared. The procedure describes hydraulic conductivity relationships better when observed values of unsaturated hydraulic conductivity are included in the curve fitting process, than when the saturated hydraulic conductivity alone is used as a matching point. Analysis of a data set taken from the literature indicates that observed air permeabilities may also be useful for estimating the unsaturated hydraulic conductivity